Fire tower tests of stair pressurization systems with overpressure relief

Stairshaft pressurization systems were investigated under various schedules of stair door operation and nonfire/fire and summer/winter conditions in a 10-story experimental fire tower. The four stairshaft pressurization systems that were tested had overpressure relief features of exit door relief, barometric damper relief, feedback control with fan bypass, and feedback control with variable-speed fan. Tests have indicated that, under the conditions tested with any one of the stair pressurization systems on, smoke contamination of the stairshaft can be expected when the stair door on the fire floor is open and the fire floor is not vented to the outdoors. Smoke contamination of the stairshaft was prevented when the fire floor was vented by means of outside wall openings; however, the stairshaft was contaminated when one or more additional stair doors were opened.
Presented at the 1990 ASHRAE Annual Meeting, St. Louis, MO, USA, June 9-13, 1990